1. Field of the Invention
This invention relates to a method for manufacturing a magneto-optical recording medium, in which at least a reproduction layer and recording layer are deposited on a substrate, and reproduction of recorded information is performed by means of domain wall displacement in the reproduction layer.
2. Description of the Related Art
Various types of rewritable magneto-optical recording media have been commercialized, in which recording marks based on magnetic domains corresponding to recording information are written in a magnetic thin film, and magneto-optical effects are employed to read this information.
Various methods have been proposed to raise the recording densities and increase the storage capacities of such magneto-optical recording media; one of those is the MSR (Magnetically Super Resolution) method, which performs ultra-high resolution reproduction surpassing the optical diffraction limit, and various MSR methods have been proposed.
For example, a DWDD (Domain Wall Displacement Detection) method has been proposed (see for example Japanese Patent Publication No. 3332458) in which a magnetic layer including a reproduction layer, recording layer and similar is deposited on a substrate, recording marks recorded in the recording layer are transferred to the reproduction layer during reproduction, and the temperature distribution within the spot of reproduction light is utilized to form a region in which the extent of domain wall displacement in the reproduction layer is increased, so that by reading recording marks, which are small compared with the diameter of the spot of reproduction light, expanded through displacement of the walls of domains in the reproduction layer, the optical diffraction limit can be surpassed.
In magneto-optical recording media employing this DWDD method, because reading is performed through displacement of the walls of domains of recording marks, particularly when adopting a land and groove recording method in which information is recorded on guide grooves or so-called grooves provided in the substrate and on so-called lands between grooves, the regions between adjacent recording tracks are the side-wall portions of the guide grooves, and magnetic separation in these side-wall portions affects the recording and reproduction characteristics.
In light of the above problem, methods have been proposed to obtain satisfactory magnetic separation by, for example, performing annealing of the side-wall portions of grooves between adjacent recording tracks using a laser or other means, rendering the magnetic layer between adjacent tracks nonmagnetic or in-plane magnetized film in this portion (see for example Japanese Patent Laid-open No. Heisei 08-147777).